The invention relates to a vacuum cleaning device comprising a dirt collection container which has a suction inlet and is in flow connection with at least one suction unit via at least one filter and at least one suction line, and comprising at least one external air inlet which opens into the at least one suction line downstream of the at least one filter and is adapted to be closed by means of at least one closing valve, the at least one closing valve having a movable valve body which, in a closed position, bears against at least one valve seat so as to form one or more sealing lines, the at least one sealing line delimiting an area which, in the closed position of the closing valve, is acted upon by a differential pressure.
Vacuum cleaning devices of this type may be designed, for example, as vacuum cleaners or else as suction sweepers. They have a dirt collection container which is adapted to be acted upon by negative pressure from one or more suction units, so that a suction stream forms and dirt is sucked into the dirt collection container under the influence of said suction stream. The dirt collection container is in flow connection with the suction unit via at least one filter and at least one suction line which follows said filter. The at least one filter permits solids, that is to say particles of dirt and dust for example, to be separated out of the suction stream. During operation of the vacuum cleaning device, more and more solids accumulate at the filter, so that the filter constitutes an increasing resistance to flow and therefore has to be cleaned. To this end, the at least one filter is adapted to be acted upon by external air, which can flow into the suction line via the external air inlet downstream of the filter, against the direction of flow which forms during suction operation. The external air used may be, for example, ambient air or else pressurized air which is pressurized by the vacuum cleaning device or stored under pressure in a storage container. During suction operation, the external air inlet is tightly closed by the at least one closing valve which is opened for filter cleaning purposes. The at least one closing valve has a movable valve body which bears in sealing manner against at least one associated valve seat during the suction operation, at least one sealing line being formed between the valve seat and the valve body and the external air inlet being tightly closed along said sealing line. The at least one sealing line delimits an area which is acted upon by a differential pressure in the closed position of the at least one closing valve.
Vacuum cleaning devices of this type are known, for example, from DE 298 23 411 U1 which proposes, for filter cleaning purposes, closing the suction inlet so that a strong negative pressure forms in the dirt collection container. A closing valve should then be opened and a filter cleaned as a result. Effective cleaning can thus be achieved but suction operation has to be completely interrupted to this end. In order to counteract this disadvantage, DE 199 49 095 A1 proposes cleaning only a subregion of the filter in each case, so that suction operation can be maintained by means of another subregion. Individual subregions of the filter are therefore cleaned one after the other, without suction operation having to be interrupted. However, the supply of external air in each case only to a subregion of the filter requires a closing valve mechanism of complicated design.
It is an object of the present invention to develop a vacuum cleaning device of the type mentioned in the introduction in such a way that the at least one closing valve is of structurally simple design and the at least one filter can be completely cleaned within a short time.